Rebecca, who married Juan in 2012, said she was shocked to receive a card from Juan for the second year in a row.

“I was surprised he was still doing it. It's been two years and he still cares very much for us both. It is incredibly heartwarming to know how much he loves us,” Rebecca told InsideEdition.com.

The couple decided to split in 2015 and Apollo, which they bought in 2013 as a puppy, went home with Rebecca to Mercedes, Texas, while Juan stayed in Houston.

Juan never stopped thinking of them, however.

This year Juan sent a long letter to Apollo and a Petco gift card for the dog's April 1 birthday.

“Watching you grow up from a puppy that fit in the palm of my hand to the overgrown big dog that you are now was nothing short of an adventure, and I loved every moment of it. There is honestly not one time where thinking of you has failed to put a smile on my face. I will forever be grateful to you for that… There isn’t a day that I don’t think of you," Juan wrote in the letter.

Juan ended the letter saying, “Take care of yourself and your mom.”

Rebecca posted the heartwarming card to Twitter, where it quickly went viral, with more than 19,000 retweets.

"It has gotten us talking again," Rebecca said. "We decided to try and work on our marriage and go to great lengths to fix the problems we came across. We are taking this all as a sign from God. We believe all of this happened for a reason."